Which one of the following substances is NOT a mixture?
- A.Ice
- B.Ice-cream
- C.Air
- D.Honey
Correct answer
Explanation
The correct answer is A, Ice. Ice is simply water in its solid state, a single compound with the fixed formula H2O, so it is a pure substance, not a mixture. A mixture contains two or more substances that are not chemically combined, keep their own properties and can be present in any proportion. A compound, by contrast, has its elements joined in a fixed ratio by mass and has properties different from those elements. Changing water into ice is only a physical change of state; the composition stays the same. Option B is wrong because ice-cream is a mixture of milk fat, sugar, water, air and flavourings, and is in fact a colloid. Option C is wrong because air is a mixture of gases, mainly nitrogen (about 78 per cent) and oxygen (about 21 per cent), with argon, carbon dioxide and water vapour, whose proportions vary from place to place. Option D is wrong because honey is a mixture of sugars such as fructose and glucose with water and small amounts of other substances. Exam tip: ice, water and steam are the same compound, H2O; air is a mixture.
Practice Questions
View allAn object is placed in front of a convex mirror. Which one of the following statements is correct?
- A.It will never form an inverted image.
- B.The image moves towards the focus when the object moves towards the mirror.
- C.Depending on the position of the object with respect to the mirror, the image can be inverted and real.
- D.The size of the image becomes larger than that of the object when the object is placed at a distance equal to half the focal length.
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For a real object anywhere in front of it, a convex mirror always gives a virtual, erect and diminished image.
Read the full explanation →When a beam of white light passes through a glass prism, the colour of light beam that deviates the least is
- A.Blue
- B.Red
- C.Green
- D.Violet
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Red light has the longest wavelength in the visible spectrum, so glass slows it the least and bends it the least.
Read the full explanation →Three equal resistors are connected in parallel configuration in a closed electrical circuit. Then the total resistance in the circuit becomes
- A.one-third of the individual resistance.
- B.two-third of the individual resistance.
- C.equal to the individual resistance.
- D.three times of the individual resistance.
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For three equal resistors R in parallel, 1/Rp = 1/R + 1/R + 1/R = 3/R, so Rp = R/3.
Read the full explanation →Sand falls vertically on a conveyor belt at a rate of 0.1 kg/s. In order to keep the belt moving at a uniform speed of 2 m/s, the force required to be applied on the belt is :
- A.0 N
- B.0.2 N
- C.1.0 N
- D.2.0 N
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The force needed equals the rate at which the belt must give horizontal momentum to the falling sand: F = v × (dm/dt) = 2 × 0.1 = 0.2 N. Newton's second law, in its general form, says force equals the rate of change of momentum.
Read the full explanation →Consider the following statements in case of terrestrial planets : I. Mercury, Venus, Earth and Mars are terrestrial planets having low densities as compared to other planets. II. They lie between the Sun and the belt of asteroids. III. Their lower gravity can hold the escaping gases. Which of the statements given above is/are correct?
- A.I and II
- B.II and III
- C.I and III
- D.II only
Show answer
The four terrestrial planets do lie between the Sun and the asteroid belt, but they are dense, not light, and their weak gravity could not hold on to escaping gases.
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